Emil fischer



UNITED STATES PATENT I OFFICE.

EMIL FISCHER, OF BERLIN, GERMA' Y, ASSIGNOR- TO 0. F. BOEHRINGER &

v SOEHNE, OF W'ALDHOF, GERMANY.

PROCESS OF MAKING HETEROXANTHI N.

srnorrrcn'rron forming part of Letters Patent No. 617,98 dated, January 17. 1899.

Griginal application filed September 7, 1897, Serial No, 6510,326- Divided and this application filed January 3, 1898. Serial ll'ol 665,462. (No specimens.) Y

To all whom it may concern: Be it known that I, EMIL Freeman, a citizen of the German Empire, residing at Berlin, in the Empire of Germany,have invented certain 5 new and useful Improvements'in Methods of Preparing Heteroxanthin; and I do hereby declare the following to be a full, clear, and exact description of the invention,such as will enable others skilled in the art to which 9 it'appertains to makev and use the same.

' This invention relates to the preparation of alkylized oxypurin's, and more particularly to the synthetical production of heteroxanthin. This body, asthe result of recent investiga- 5 tions, was recognized as monomethyl-xanthin by Kriiger and Salomon. (See Zeitschrz'ft fit) Physiologische C'hemie, Vol. 21, page 169.) More recent researches by myself have shown this body to be a methylized oxypurin.

So far as I am aware heteroxanthin has hitherto been obtained only as a secretion formed in the animal organism, no one having pm- I duced it synthetically. I have discovered a 7 method of thus producingheteroxanthin from theobromin; and my present invention consistsin this method and such other steps, features, and subprocesses as will be hereinafter set forth, and pointed-out in the claims.

In explaining my invention the nomenclao-ture recently proposed by me (Sitzzm sbe r- .e'chte der Kdnigl. Preussz'schen Ale-ac e-m'z'e,

1887, No. 1, January 8, 1897, and Berichte de'r Deuts'chen Ohe-misohen Gesellschaft, Vol. 30, page 557) and the structural formulze adopted as the result of the most recent investigations willbefollowed. Accordingtothisnomenclature the various atoms of the pu'rin'molecule whichforms the basis of the uric acid and xanthin molecules and many others are num- .o. bored as follows: Y

- I (UN-0(6):...

5 I I -N(7 may be eliminated and replaced by hydroxyl results in the loss of tions as a guide" the equivalent terms hereim after used for the starting material-the theobromine-and the resultant bodyheteroxanthin as well as \the intermediate body obtained, will be apparent and clearly understood.

' The structural form ulze and consequent additional designations to be appropriated to the theobromin and heteroxanthin are as follows:

First. Theobrom'in HN+OO or 3-7-dimethyl-2-6-dioxy- 0H,.N-Gltpurin.

or 3-7-dimethyla xantl1in Second. Heteronanthin HN-C.O I

or 7-methyl-xanthin OG bromin, treating it with a phosphorus oxyhalogen compound, such as phosphorus ox-ychlorid. .Under this treatment the oxygen atoms are replaced by chlorin and one methyl radical is split off, the resultant body being 7-1nethyl-2(i-dichloropurin: v Y

01.0 c-Non, l l \O N-Q-N v The two chlorin atoms of this nevv bodymethyldichloropurin- -are very mobile. They simultaneously or separately.

The present invention-"involves the concurrent removal of both'chlorin atoms-by heator treating the dichloropurin together with an acid, such as hydrochloric acid. ThlS' both chlorin atoms and zoo the formation of heteroxanthin', according to the equation:

IiN-o I will now give a detailed description of the phosphorus oxychlorid, to a temperature of- 140 centigrade, this temperature being maintained for three hours and the mass constantly agitated. A clear liquid having a pale-brown color results. From this liquid the remaining phosphorus oxyehlorid is removed by dis tilling in uacuo. One hundred and fifty parts of cold water having a temperature of be- :tween 0 and centigrade, preferably, are

then poured over the amorphous residue. Under this treatment the mass "is gradually converted into al most colorless crystals. This change is hastened by shaking The generation of heat in the mass is obviated by cooling with ice or other refrigerant agency. The mass after having been finally cooled thoroughly is put on the filterand washed with ice-water. The crude product so obtained is contaminated with a substance which is soluble in alkali. out with an alkaline solution, preferably-very dilute soda-lye of about one per cent. strength. The solid residue is then'drai'ned on a filter and well washed thereon and redissolved in hot water and recrystallized therefrom. The new compound 7-methyl-26-dichloropurin so obtained crystallizes in line colorless needles, which melt at about 196 to 197 centigrade. It is soluble with difficulty in cold water and soluble in aboutseventy parts hot water and in about thirty parts boiling alcohol. Its composition is indicated by the formula C ILrLCh or the structural formula:

The samev is hence dissolved same from theobrom'in'is indicated in the equation:

Second. Preparation of heier0a'(uzi7zin.-.I take one part of 7-methyl-2-6-dichloropurin and heat the same under pressure-42. g., in a. pressure-tnbe.together with ten parts of hydrochloric acid of the specific gravity 1.19, to fr0ml20 to 125 centigrade, ma'intainin g this temperature for three hours. A clear faintlycolored solution res'nlts,whichon being evaporated to' dryness on the water bath leaves the 'hydrochlorate of the heteroxanthin or methylxanthin inthe shape of coarse pgismatic crystals. The reaction takes place according to the followirig equation:

lute ammonia is poured over these crystals in suificient or more than sufficient quantity to combine with all of the 1101. Any excess of ammonia is removed by evaporation. The diflicultly-soluble base is then drained on tho filter and redissolved in hot water, the solution being then allowed to cool. The base is IIO ' T0 liberate the base heteroxanthindithus obtained as a colorless indistinctly-crys talline powder. To obtain the base in an absolutelypure condition, it is purified by first preparing. the sodium salt, which forms good crystals.

. The heteroxanthin or 7.-methyl-xanthin or 7-methyl-2-6-dioxypurin coincides in most respects with the .heteroxanthin, which has been investigated'and described by Kruger .and Salomon (Zeitschrifl fitr Physwlog sche C'hemie, Vol. 21, page 169) as well as Bondzynski and Gottlieb, (Berz'chie der Deutschen Ohemz'schen Gesellschafi, Vol. 28, 1895,'page Eapcrinzenlulc Patholo- 87, page 385.) A difr cheeryed withregard to melti1.., p and the solubility of the e water, the varying data found by the mer investigations being due to the imp :ity ct theingrcdients or reagents em pioyed.

l find that pure heteroxanthin has no fixed melting-point, but begins to soften when heated to over 360 centigrade and melts at about 380 centigrade, this change being accompanied by a darkening of the compound and the evolution of gases. One hundred and forty-two parts, by weight, of boiling water are required to dissolve one part of heteroxanthin.

The 7-methyl-2 G-dichloropurin herein described, together with its method of manufacture, forms the subject-matter of the claims of my application, Serial No. 650,826, filed- September 7, 1897, (of which this is a divisional application,) and is there shown to be the secondary starting material for the series of processes and compounds described in illustration of the invention. They are hence not claimed herein, being merely described for the purpose of a full and sufficient disclosure of my present invention.

It will be seen from the above that my in-v vention is not confined to the specific details shown in illustration of the same 3 but, broadly considered, it consists in the treatment of methyldichloropurin with a mineral acid and also in the conversion of theobromin into the n1ethyl-dichloropurin, together with subsequent treatment of the .latter with minera]v acid.

Having thus fully described my invention, what I claim, and desire to secure by Letters Patent of the United States, is-

1. In the art of preparingheteroxanthin, the I oxanthin, which consists in converting theobromi'n into 7-methyl-2-6-dichloropurin and then treating thelatter with a mineral acid.

'5. The method which consists in heating theobromin with phosphorous oxychlorid and purifying the resultant 'T-methyl-Q-G-dichloropurin, then heating the latter, witha mineral acid.

In testimony whereof I affix my signature in presence of two witnesses.

IL FISCHER.

Witnesses CHAS. H. DAY, HENRY HASPER. 

